Scanner is a popular office machine used widely for image capture application. To increase document feeding speed, a scanner equipped with an auto document feeding mechanism is therefore developed. However, when user operates a conventional flatbed scanner to scan a book, an upper cover of the scanner has to be manually lifted up for scanning operation.
FIG. 1A is a prior art scanner disclosed in the U.S. Pat. No. 7,619,789. The scanner shown in FIG. 1A includes an upper cover 1, a housing 2 and a connecting mechanism 3, in which, the connecting mechanism 3 further includes a first axle 31, a second axle 32 and a pivoting plate 33.
The connecting mechanism 3 is used to connect the upper cover 1 and the housing 2, to rotate the upper cover 1 with respect to the housing 2. In FIG. 1A, the first axle 31 connecting pivotally the upper cover 1 to the pivoting plate 33, rotates the upper cover 1 with respect to the housing 2 to about 40 arc degrees. At the moment, the second axle 32 is disposed in the axle center A1, and the pivoting plate 33 is not with respect rotated with respect to the housing 2.
Please refer to FIGS. 1B and 1C, the second axle 32 connecting pivotally the pivoting plate 33 to the housing 2, in case of scanning a book or a big size document, the upper cover 1 and the pivoting plate 33 can be lifted up to shift the second axle 32 into the axle center A2, to enable the upper cover 1 and the pivoting plate 33 to rotate with respect to the housing 2 to more than 180 arc degrees.
To the aforementioned upper cover opening mechanism of the prior art scanner, there are some drawbacks needed to be improved. First, the mentioned scanner of the prior art is inapplicable to a scanner with an auto document feeder. That is because the upper cover of the scanner with the auto document feeder is quite massive and hard to a general user to lift up the upper cover 1 to change its axle center location. In addition, the axle used for the scanner of the prior art is unbearable to the weight of the upper cover equipped with the auto document feeder and thereby affecting the useful life of life-span of the axle.
Second, even though it is not applied to the scanner with the auto document feeder, the prior scanner has several drawbacks when scanning a book or a larger size document, as described as follows. Please refer to FIG. 1D, take scanning the two adjacent pages B1 and B2 as an instance. FIG. 1D shows a situation of scanning page B1. After the page B1 has been scanned, it has to move B1 toward the upper cover 1 in order to successively put the page B2 onto the flatbed of the scanner for scan, that is, user needs to lift the upper cover up to a larger angle to accommodate the page B1 of the book B. However, if there is a room limitation or an obstacle adjacent to the scanner, the turning operation of the upper cover is unavoidable interfered and hard to turn directly to over 180 arc angles to accommodate B1. Then a compromised orientation change of 180 degrees for B2 scanning is unavoidable, and an undesired 180 degrees difference of the scanned images for B1 to B2 is induced. To align the images orientation of B1 to B2, a further image adjusting operation is necessarily, however that is extra and inconvenient operation to user.